"a raise would indicate that i have something better than just the average hand,"

Well, you *do* have an average hand. no more no less. There is more to raising than just doing it: you need to consider what you opponent will see. your raise gives the big blind 3:1 odds on his call- all s/he has to have is a 25% chance of winnining to make the play break even:
(+3)*25% + (-1)*75% = 0